Can you dyno an automatic

I questioned the operator who begrudging agreed to re-run it using a higher gear. It made 40rwhp more!!! Final figures where hp flywheel. However I think this is a bit high, and if you look at the graph there is a torque spike from the converter when it shifted gears.

If you profile the graph it reads a PEAK of hp flywheel which is about bang on what these should make. HD Adam 4, posts months. Why on earth would you try and get a dyno figure in first gear?

To get a realistic number, you need to be in whatever gear gives you a 1 to 1 ratio and at a high enough RPM that the converter is locked up. Some dyno operators do a funky coast down test which is supposed to calculate your transmission losses and give you a BHP figure but I wouldn't put too much faith in that. The figures you achieve will almost certainly not correspond to anybody elses figures unless you both go to the same dyno on the same day and use the same correction figures.

Cupramax 9, posts months. When you're remapping a car you're trying to turn the boost up to a sensible limit, and configure the boost controller to have it hold where you want it to. Then you're leaning the fuel out to get the perfect AFR, and you're advancing the ignition as far as you can before it knocks. Boost is measured by a boost gauge. AFR is measured using an exhaust probe. Det is measured with cans, or knock count on the ECU.

There's no need for a dyno. The dyno is generally used after tuning to work out the power gain. As part of the calculation, it uses the speed of the rollers as an input. For manual transmissions, for a given gear, there would be a constant relationship between engine speed and road speed and so the results can be displayed as power vs Engine Speed RPM , a more common format.

What happens with automatic transmissions? With the torque converter between the engine and the transmission, the relationship between engine speed and road speed is no longer constant. So, what to do about engine speed? In the correct scenario you will put your transmission into the 3rd gear position manually and make the dyno run from that position only. By doing this the valve body routes fluid differently and forces the overdrive roller clutch to engage with the direct clutch , keeping the overdrive roller clutch protected.

This can happen even if you are electronically shifting the transmission into the 3rd gear. Driving in the manual ranges while on the chassis dyno will back up the roller clutch with the overrun clutch.